title: Correlation of dynamic changes in γ-H2AX expression in peripheral blood lymphocytes from head and neck cancer patients with radiation-induced oral mucositis.
abstract: BACKGROUND
  To evaluate the role of γ-H2AX in peripheral blood lymphocytes (PBLs) as a predictive biomarker of the severity of oral mucositis (OM) in head and neck cancer (HNC) patients with receiving radiotherapy.
  
  
  METHODS
  In vitro assays for evaluating DNA damage and repair kinetics were performed on blood samples withdrawn from 25 HNC patients undergoing radiotherapy or chemoradiotherapy before radiotherapy. As for the in vivo study, blood samples were also withdrawn before radiotherapy, and 1 hour after radiotherapy on the fourth and last days. Flow cytometry was used to assess the expression of γ-H2AX in PBLs. OM was assessed using the World Health Organization (WHO) scores twice a week and correlated with the expression of γ-H2AX.
  
  
  RESULTS
  The in vitro assay results showed that patients with severe OM had higher γ-H2AX-specific relative fluorescence at various irradiation doses in the damage kinetics assay, with significantly higher γ-H2AX expression at 8 Gy (p = 0.039), and also at 24 hours after irradiation at a dose of 2 Gy in the repair kinetics assay, compared to the patients with mild OM (p = 0.008). The optimal cutoff value for relative fluorescence of γ-H2AX was 0.960, 24 hours post-irradiation. However, there were no significant differences in γ-H2AX expression at different times between the two groups, as assessed with the in vivo assay.
  
  
  CONCLUSIONS
  These results suggest that the damage and repair kinetics of γ-H2AX from PBLs in the in vitro study may have predictive value for identifying the grades of OM among HNC patients prior to radiotherapy.
authors.affiliation: Department of Radiation Oncology, Sixth People's Hospital of Jiao Tong University, Shanghai 200233, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Cheng-run
authors.initials: CR
authors.lastname: Du
authors.forename: Wen-cai
authors.initials: WC
authors.lastname: Xu
authors.forename: Ze-liang
authors.initials: ZL
authors.lastname: Shi
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Zhao-bin
authors.initials: ZB
authors.lastname: Li
authors.forename: Shen
authors.initials: S
authors.lastname: Fu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D014408:Biomarkers, Tumor / Q000097:blood; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005434:Flow Cytometry; D006258:Head and Neck Neoplasms / Q000378:metabolism / Q000532:radiotherapy*; D006657:Histones / Q000096:biosynthesis*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011829:Radiation Dosage; D011878:Radiotherapy / Q000009:adverse effects*; D013280:Stomatitis / Q000209:etiology / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C468783:H2AX protein, human; D006657:Histones